For example, in an image-reading apparatus used in a facsimile, a copying machine, a scanner, and the like, a contact-type image sensor that reads image information on a document at the same magnification is used.
FIG. 11A depicts a view illustrating an example of a schematic cross-section showing the positional relationship between a conventional contact-type image sensor unit (hereinafter, abbreviated as a “CIS unit”) 101 and a document 102 that is in contact with a transparent cover glass 103 in an image-reading apparatus (see Patent document 1).
In FIG. 11A, the CIS unit 101 has a linear illuminator 106 including an LED array that illuminates the document 102, and a rod lens array 109 that forms an image of light reflected from the document 102. Furthermore, a light-receiving sensor 110 in which photoelectric conversion elements for photoelectrically converting light whose image has been formed by the rod lens array 109 are arranged, a printed circuit board 111 on which the light-receiving sensor 110 and the like are mounted, and a frame 112 for holding these constituent elements are included.
In the CIS unit 101, it is desired that the distance from the rod lens array 109 to the image sensor array 110 is set in an optically accurate manner and fixed, and that an optical path line from a reading line on the document 102 illuminated by the linear illuminator 106 to the light-receiving sensor 110 and an optical axis of the rod lens array 109 are caused to accurately match each other by positioning and fixing these constituent elements on the frame 112.
In the conventional example shown in FIGS. 11A and 11B, the rod lens array 109 is positioned and fixed as follows: first, a spring 119 disposed between the frame 112 and the rod lens array 109 is caused to press against one side face of the rod lens array 109, and the other side face of the rod lens array 109 is brought into contact with projecting portions 115 arranged at a corresponding face of the frame 112, and, thus, the rod lens array 109 is positioned. Next, an adhesive 113 is caused to permeate through a gap between the frame 112 and the side face of the rod lens array 109 formed at the projecting portions 115, and thus, the constituent elements are adhered and fixed to each other.
Conversely, in the conventional example in FIG. 12, instead of a method in which the rod lens array 109 is fixed with a set screw screwed from a screw hole that is formed in the frame 112, a method in which an adhesive made of an ultraviolet-curable resin is used to fix the rod lens array 109 to the frame 112 is shown (Patent document 2). Here, FIG. 12 is a cross-sectional view of the CIS unit taken along a cutting line that is perpendicular to the longitudinal direction as in FIGS. 11A and 11B, and constituent elements in this drawing having the same function or name as that in FIGS. 11A and 11B are denoted by the same reference numerals.
In this conventional example, a vertical face 107 that is disposed on a frame (referred to as a “chassis” in Patent document 2), with which the side face of the rod lens array 109 is brought into contact for positioning, has a plurality of grooves 120 that extend in the longitudinal direction, and the ultraviolet-curable adhesive 113 is applied to the grooves 120. Subsequently, the rod lens array 109 is pressed against the vertical face so as to be pressed after positional adjustment, ultraviolet rays are irradiated from an ultraviolet-irradiating apparatus 121 through through-holes 117 for ultraviolet irradiation, and, thus, the adhesive 113 is cured and the constituent elements are fixed.